Can you weld unions?

I've been trying for ages now, using scripts I've made and also trying welding plugins, but I can't find how.

My current script

local w1 = Instance.new("Weld")
    w1.Parent = script.Parent.PLT 
    w1.Part0 = w1.Parent
    w1.Part1 = script.Parent.C 

    local w2 = Instance.new("Weld")
    w2.Parent = script.Parent.PLT
    w2.Part0 = w1.Parent
    w2.Part1 = script.Parent.A 

    local w3 = Instance.new("Weld")
    w3.Parent = script.Parent.PLT
    w3.Part0 = w1.Parent
    w3.Part1 = script.Parent.J 

    local w4 = Instance.new("Weld")
    w4.Parent = script.Parent.PLT
    w4.Part0 = w1.Parent
    w4.Part1 = script.Parent.Part   
end